Flat gripper actuator

ABSTRACT

Examples described here include a device that has a housing defining a cavity, and a force sensor. The device also includes a first hydraulic actuator positioned in the cavity, and a second hydraulic actuator positioned in the cavity. The first and second hydraulic actuators move between respectively relaxing modes and thrusting modes along respective longitudinal axes. The longitudinal axis of the first hydraulic actuator is substantially parallel to the longitudinal axis of the second hydraulic actuator. The device also includes a first actuated member coupled to the first hydraulic actuator, and a second actuated member coupled to the second hydraulic actuator.

BACKGROUND

Robotic systems, such as a robotic arm containing a gripping component,may be used for applications involving picking up or moving objects. Forinstance, a robotic device may be used to create a stack of objects,load objects to a given area, or unload objects from a given area. Insome cases, all of the objects that the robotic system is to manipulatemay be of the same type. In other cases, such objects may have varyingweights and sizes. Further, such robotic systems may direct a roboticarm to pick up objects based on predetermined knowledge of where objectsare in the environment. Such robotic systems may also direct a roboticarm to pick up objects based on predetermined knowledge of what types ofobjects the robotic arm can manage (e.g., based on whether a gripper orother robotic manipulator can support a weight of the object whilemoving or otherwise interacting with the object at variousaccelerations).

SUMMARY

Example systems and methods may provide for actuating a robotic gripperthat includes at least two hydraulic actuators positioned parallel toone another in respective cavities of the palm of the robotic gripper.The hydraulic actuators may be coupled to actuated members for grippingvarious objects. By placing the hydraulic actuators in the plane of thepalm of the robotic gripper, the height of the palm is minimized. Byreducing the palm height, the effective payload is increased and theworkspace reorientation envelope is reduced in size.

In one aspect, the present application describes a device. The devicemay include a housing defining a cavity. The device may further includea force sensor. The device may further include a first hydraulicactuator positioned in the cavity, wherein the first hydraulic actuatormoves between a first relaxing mode and a first thrusting mode along alongitudinal axis of the first hydraulic actuator based at least in partin response to sensor data from the force sensor. The device may furtherinclude a second hydraulic actuator positioned in the cavity, whereinthe second hydraulic actuator moves between a second relaxing mode and asecond thrusting mode along a longitudinal axis of the second hydraulicactuator based at least in part in response to sensor data from theforce sensor, and wherein the longitudinal axis of the first hydraulicactuator is substantially parallel to the longitudinal axis of thesecond hydraulic actuator. The device may further include a firstactuated member coupled to the first hydraulic actuator, wherein thefirst actuated member is in a first open mode when the first hydraulicactuator is in the first relaxing mode, and wherein the first actuatedmember is in a first closed mode when the first hydraulic actuator is inthe first thrusting mode. The device may further include a secondactuated member coupled to the second hydraulic actuator, wherein thesecond actuated member is in a second open mode when the secondhydraulic actuator is in the second relaxing mode, and wherein thesecond actuated member is in a second closed mode when the secondhydraulic actuator is in the second thrusting mode.

In another aspect, the present application describes a robotic device.The robotic device may include a first limb, and a second limb coupledto the first limb. The robotic device may further include a grippingcomponent coupled to the second limb, wherein the gripping componentcomprises (i) a housing defining a cavity, (ii) a force sensor, (iii) afirst hydraulic actuator positioned in the cavity, wherein the firsthydraulic actuator moves between a first relaxing mode and a firstthrusting mode along a longitudinal axis of the first hydraulicactuator, (iv) a second hydraulic actuator positioned in the cavity,wherein the second hydraulic actuator moves between a second relaxingmode and a second thrusting mode along a longitudinal axis of the secondhydraulic actuator, and wherein the longitudinal axis of the firsthydraulic actuator is substantially parallel to the longitudinal axis ofthe second hydraulic actuator, (v) a first gripping member coupled tothe first hydraulic actuator, and (vi) a second gripping member coupledto the second hydraulic actuator. The robotic device may further includea controller comprising at least one processor and data storagecomprising instructions executable by the at least one processor tocause the controller to perform operations. The operations may include,based at least in part in response to sensor data from the force sensor,causing the first and second hydraulic actuators to move between thefirst and second relaxing modes and the first and second thrusting modesto thereby cause movements of the first and second gripping memberstoward each other so as to grasp one or more objects.

In another aspect, the present application describes a method foractuating a device comprising (i) a housing defining a cavity, (ii) aforce sensor, (iii) a first hydraulic actuator positioned in the cavity,wherein the first hydraulic actuator moves between a first relaxing modeand a first thrusting mode along a longitudinal axis of the firsthydraulic actuator, (iv) a second hydraulic actuator positioned in thecavity, wherein the second hydraulic actuator moves between a secondrelaxing mode and a second thrusting mode along a longitudinal axis ofthe second hydraulic actuator, and wherein the longitudinal axis of thefirst hydraulic actuator is substantially parallel to the longitudinalaxis of the second hydraulic actuator, (v) a first gripping membercoupled to the first hydraulic actuator, and (vi) a second grippingmember coupled to the second hydraulic actuator. The method may involvereceiving, at a control system configured to actuate the device, dataindicative of a distinct location of an object in an environment of thedevice and further indicative of a dimension of the object. The methodmay also involve, based on the location and dimension of the object,determining a position to which to rotate each of the first and secondgripping members such that the object is located between the first andsecond gripping members. The method may further involve causing thefirst and second gripping members to rotate to the determined position.The method may still further involve, receiving, at the control system,sensor data from the force sensor. The method may yet still furtherinvolve, in response to the received sensor data, causing movement ofthe first and second gripping members so as to grasp the object.

In yet another aspect, a system is provided that includes a means foractuating a device comprising (i) a housing defining a cavity, (ii) aforce sensor, (iii) a first hydraulic actuator positioned in the cavity,wherein the first hydraulic actuator moves between a first relaxing modeand a first thrusting mode along a longitudinal axis of the firsthydraulic actuator, (iv) a second hydraulic actuator positioned in thecavity, wherein the second hydraulic actuator moves between a secondrelaxing mode and a second thrusting mode along a longitudinal axis ofthe second hydraulic actuator, and wherein the longitudinal axis of thefirst hydraulic actuator is substantially parallel to the longitudinalaxis of the second hydraulic actuator, (v) a first gripping membercoupled to the first hydraulic actuator, and (vi) a second grippingmember coupled to the second hydraulic actuator. The system may alsoinclude a means for receiving data indicative of a distinct location ofan object in an environment of the device and further indicative of adimension of the object. The system may further include a means forbased on the location and dimension of the object, determining aposition to which to rotate each of the first and second grippingmembers such that the object is located between the first and secondgripping members. The system may still further include a means forcausing the first and second gripping members to rotate to thedetermined position. The system may yet still further include a meansfor receiving sensor data from the force sensor. The system may yetstill further include a means for in response to the received sensordata, causing movement of the first and second gripping members so as tograsp the object.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects,implementations, and features described above, further aspects,implementations, and features will become apparent by reference to thefigures and the following detailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an operational block diagram illustrating a robotic device,according to an example implementation.

FIG. 2A illustrates a cross-sectional view of a robotic gripper in arelaxed mode, according to an example implementation.

FIG. 2B illustrates a cross-sectional view of the robotic gripper ofFIG. 2A in a gripping mode, according to an example implementation.

FIG. 2C illustrates an element of the component of FIG. 2A, according toan example implementation.

FIG. 2D illustrates an element of the component of FIG. 2A, according toan example implementation.

FIG. 2E illustrates an element of the component of FIG. 2A, according toan example implementation.

FIG. 3A illustrates a robotic gripper, according to an exampleimplementation.

FIG. 3B illustrates an element of the component of FIG. 3A, according toan example implementation.

FIG. 3C illustrates example gripping members, according to an exampleimplementation.

FIG. 3D illustrates example gripping members, according to an exampleimplementation.

FIG. 4 is a flow chart of an example method, in accordance with at leastsome implementations described herein.

DETAILED DESCRIPTION

Example methods and systems are described herein. Any exampleimplementation or feature described herein is not necessarily to beconstrued as preferred or advantageous over other implementations orfeatures. The example implementations described herein are not meant tobe limiting. It will be readily understood that certain aspects of thedisclosed systems and methods can be arranged and combined in a widevariety of different configurations, all of which are contemplatedherein.

Furthermore, the particular arrangements shown in the Figures should notbe viewed as limiting. It should be understood that otherimplementations might include more or less of each element shown in agiven Figure. Further, some of the illustrated elements may be combinedor omitted. Yet further, an example implementation may include elementsthat are not illustrated in the Figures.

In the following description the term “substantially” may be used suchthat the recited characteristic, parameter, or value need not beachieved exactly, but that deviations or variations, including forexample, tolerances, measurement error, measurement accuracylimitations, manufacturing deviations and other factors known to skillin the art, may occur in amounts that do not preclude the effect thecharacteristic was intended to provide.

In addition, in the following description, the terms “robotic gripper,”“actuated member,” “gripping member,” and “robotic manipulator” may beused interchangeably to refer to a component of a robotic deviceoperable to manipulate objects (e.g., grab, move, drop, etc.).

In practice, robotic gripper operation can be limited in various ways.By way of example, the maximum effective payload of an example grippermay be limited due to a distance between a palm of the gripper and awrist of the gripper. Such a distance between the wrist and an objectgrabbed by the gripper defines a moment arm, therefore decreasing thedistance between the palm and the wrist may be advantageous. Therefore,it may be desirable to have a robotic gripper with a decreased palmheight in order to facilitate efficient object manipulation.

Described herein is a robotic device including such a gripper apparatusand further including a control system configured to actuate thegripper. Unless otherwise indicated herein, it should be assumed thatactuation of the gripper and its various components is controlled eitherdirectly or indirectly by such a control system.

In some embodiments, such a device may include a housing defining acavity, and a force sensor. The device may further include a firsthydraulic actuator positioned in the cavity. The first hydraulicactuator moves between a first relaxing mode and a first thrusting modealong a longitudinal axis of the first hydraulic actuator. The firsthydraulic actuator may be configured to move between the first relaxingmode and the first thrusting mode based at least in part in response tosensor data from the force sensor. For example, the sensor data may beindicative of the gripper contacting an object. The device may furtherinclude a second hydraulic actuator positioned in the cavity. The secondhydraulic actuator may be configured to move between a second relaxingmode and a second thrusting mode along a longitudinal axis of the secondhydraulic actuator based at least in part in response to sensor datafrom the force sensor. The longitudinal axis of the first hydraulicactuator is substantially parallel to the longitudinal axis of thesecond hydraulic actuator. The gripper may further include a firstactuated member coupled to the first hydraulic actuator, and a secondactuated member coupled to the second hydraulic actuator.

In operation, the first actuated member may be configured to be in afirst open mode when the first hydraulic actuator is in the firstrelaxing mode, and in a first closed mode when the first hydraulicactuator is in the first thrusting mode. Similarly, the second actuatedmember may be configured to be in a second open mode when the secondhydraulic actuator is in the second relaxing mode, and in a secondclosed mode when the second hydraulic actuator is in the secondthrusting mode.

The device may also include a control system to actuate the actuatedmembers. The control system can perform various operations with respectto such an arrangement for a gripper apparatus. By way of example, thecontrol system can cause the actuated members to grasp an object. Forinstance, the control system may receive data indicative of an object inan environment of the robotic device, the data including a location ofthe object in the environment. Based on the location of the object, thecontrol system may determine a position to which to rotate each of thefirst and second actuated members such that the object is locatedbetween the first and second actuated members. The control system mayfurther cause the first and second actuated members to rotate to thedetermined position, and further cause movement of the first and secondactuated members so as to grasp the object.

It should be understood that the above examples are provided forillustrative purposes, and should not be construed as limiting. As such,the implementations herein may additionally or alternatively includesother features or includes fewer features, without departing from thescope of the invention.

Reference will now be made in more detail to various implementations ofthe robotic device described above, examples of which are illustrated inthe accompanying drawings. In the following detailed description,numerous specific details are set forth in order to provide a thoroughunderstanding of the present disclosure and the describedimplementations. However, the present disclosure may be practicedwithout these specific details. In other instances, well-known methods,procedures, components, and circuits have not been described in detailso as not to unnecessarily obscure aspects of the exampleimplementations.

FIG. 1 is a functional block diagram illustrating a robotic device 100,according to an example implementation. The robotic device 100 couldinclude various subsystems such as a mechanical system 102, a sensingsystem 104, a control system 106, as well as a power supply 107. Therobotic device 100 may include more or fewer subsystems and eachsubsystem could include multiple elements. Further, each of thesubsystems and elements of robotic device 100 could be interconnected.Thus, one or more of the described operations of the robotic device 100may be divided up into additional operational or physical components, orcombined into fewer operational or physical components. In someexamples, additional operational and/or physical components may be addedto the examples illustrated by FIG. 1.

The mechanical system 102 may include components such as a robotic arm108, a gripper 110, and a motor 112. The robotic arm 108 may include afirst limb 109 coupled to a second limb 111, and the gripper 110 may becoupled to the second limb. Motor 112 may be an electric motor poweredby electrical power, or may be powered by a number of different energysources, such as a gas-based fuel or solar power. Additionally, motor112 may be configured to receive power from power supply 107. The powersupply 107 may provide power to various components of robotic device 100and could represent, for example, a rechargeable lithium-ion orlead-acid battery. Other power supply materials and types are alsopossible.

One or more encoder(s) 113 may be coupled to the gripper 110. Inparticular, the gripper 110 may include a first gripping member and asecond gripping member. In such an example, a first encoder may becoupled to the first gripping member to provide data indicative ofmotion of the first gripping member. Similarly, a second encoder may becoupled to the second gripping member to provide data indicative ofmotion of the second gripping member. For example, the encoder(s) 113may include a rotary encoder, a shaft encoder, or any otherelectro-mechanical device configured to convert an angular or linearposition/motion of the first gripping member and/or second grippingmember to an analog or digital signal (e.g., the data, etc.). Variousimplementations are possible for the encoder(s) 113 such as mechanical(e.g., metal disc containing a set of concentric rings of openings),optical (e.g., glass/plastic with transparent and opaque areas),magnetic (e.g., disc that includes a series of magnetic poles),capacitive (e.g., asymmetrical shaped disc rotated within the encoder toadjust capacitance between two electrodes), or any other implementation.

In some examples, the data provided by the encoder(s) 113 may indicate achange in a position (e.g., orientation) of, respectively, the firstgripping member and/or the second gripping member of the gripper 110.Further, for example, the encoder(s) 113 may provide a signal (e.g.,index pulse, etc.) indicative of the first gripping member and/or thesecond gripping member being at a particular orientation.

Accordingly, in some examples, the encoder(s) 113 may include anincremental encoder configured to provide the data indicative of achange in the orientation of the first gripping member and/or the secondgripping member of the gripper 110. In these examples, the device 100may cause a first actuator to rotate the first gripping member and/or asecond actuator to rotate the second gripping member, respectively,until the signal (e.g., index pulse, etc.) of the encoder(s) 113 isdetected to determine the particular orientations of the first grippingmember and/or the second gripping member.

Additionally or alternatively, in some examples, the encoder(s) mayinclude an absolute encoder configured to provide the data. The absoluteencoder, for example, may be configured to detect motion/change inorientations of the first gripping member and/or the second grippingmember even if the absolute encoder is not provided with power. In theseexamples, the encoder(s) 113 may provide the data indicative of theorientations of the first gripping member and/or the second grippingmember without the device 100 rotating a given gripping member until thesignal (e.g., index pulse) is received from the encoder(s).

The sensing system 104 may use one or more sensors attached to a roboticarm 108, such as sensor 114. The sensing system 104 may also use one ormore sensors attached to the gripper 110, such as sensor 116. Withinexamples, these sensors may include force or torque sensors that can bemounted on the robotic arm and/or gripper and thereby senseforces/torques experienced by the robotic arm and/or by one or moregripping fingers (or other gripping surfaces) of the gripper.Additionally or alternatively, these sensors may include camerasconfigured to acquire images of the environment of the robotic device.Additionally or alternatively, these sensors may include 2D sensorsand/or 3D depth sensors that sense information about the environment asthe robotic arm 108 and/or the gripper 110 moves. The sensing system 104may determine information about the environment that can be used bycontrol system 106 (e.g., a computer running motion planning software)to navigate the robotic arm and/or gripper through the workplace into aposition for picking and moving objects efficiently, for instance. Thecontrol system 106 could be located on the device or could be in remotecommunication with the device.

In some arrangements of the robotic device 100, the power supply 107 maysupply power to the gripper 110 (e.g., to the fingers or other grippingsurface(s) of the gripper) to be transmitted in turn from the gripper tovarious devices that the gripper is grasping or otherwise in contactwith. Within examples, power may be transmitted through the gripper topower specialized tools such as drivers, wrenches, drills, cutters,saws, etc. Within additional examples, the gripper may contact arechargeable battery or other device in need of power in order totransmit power to that device. To facilitate such a transmission ofpower in practice, plated contact pads or similar electrical contactsmay be present on both the gripper and the devices that the grippertouches, in order to establish an electrical connection between thegripper and those devices.

Many or all of the operations of robotic device 100 could be controlledby control system 106. Control system 106 may include at least oneprocessor 118 (which could include at least one microprocessor) thatexecutes instructions 120 stored in a non-transitory computer readablemedium, such as the memory 122. The control system 106 may alsorepresent a plurality of computing devices that may serve to controlindividual components or subsystems of the robotic device 100 in adistributed fashion. Within examples, control system 106 may beconfigured to control operation of the gripper 110. Alternatively, therobotic device may include a control system for the gripper that isseparate from control system 106 and that is configured to access datafrom and share data with control system 106.

In some implementations, memory 122 may contain instructions 120 (e.g.,program logic) executable by the processor 118 to execute variousoperations of robotic device 100, including those described inconnection with FIGS. 2A, 2B, 2C, 2D, and 2E, and FIGS. 3A, 3B, 3C, and3D below. Memory 122 may contain additional instructions as well,including instructions to transmit data to, receive data from, interactwith, and/or control one or more of the mechanical system 102, thesensing system 104, and/or the control system 106.

FIG. 2A is a side view of an example gripper 200, according to anexample embodiment. As shown in FIG. 2A, the gripper 200 may include ahousing 202 defining a cavity 204. The housing 202 may define a palm ofthe gripper 200. The gripper 200 may also include a force sensor 206positioned inside of the cavity 204. In another example, the forcesensor 206 may be positioned adjacent to and outside of the cavity 204.Other locations for the force sensor 206 are possible as well. Thegripper 200 may further include a first hydraulic actuator 208positioned in the cavity 204. The first hydraulic actuator 208 movesbetween a first relaxing mode and a first thrusting mode along alongitudinal axis of the first hydraulic actuator 210. The firsthydraulic actuator 208 is shown in the first relaxing mode in FIG. 2A.The first hydraulic actuator 208 may be configured to move between thefirst relaxing mode and the first thrusting mode based at least in partin response to sensor data from the force sensor 206. For example, thesensor data may be indicative of the gripper 200 contacting an object.As another example, the sensor data may be indicative of the gripper 200contacting a surface on which the object is resting. Other examples offorce sensor data are possible as well.

The gripper 200 may further include a second hydraulic actuator 212positioned in the cavity 204. The second hydraulic actuator 212 may beconfigured to move between a second relaxing mode and a second thrustingmode along a longitudinal axis of the second hydraulic actuator 214. Thesecond hydraulic actuator 212 is shown in the second relaxing mode inFIG. 2A. Similar to the first hydraulic actuator 208, the secondhydraulic actuator 212 may be configured to move between the secondrelaxing mode and the second thrusting mode based at least in part inresponse to sensor data from the force sensor 206. As shown in FIG. 2A,the longitudinal axis of the first hydraulic actuator 210 issubstantially parallel to the longitudinal axis of the second hydraulicactuator 214. The gripper 200 may further include a first actuatedmember 216 coupled to the first hydraulic actuator 208, and a secondactuated member 218 coupled to the second hydraulic actuator 212.

By placing the hydraulic actuators 208, 212 in the plane of the housing202 of the gripper 200, the height of the housing 202 can be minimized.As such, a profile of the housing 202 may be defined by a height of thefirst hydraulic actuator 208 and a height of the second hydraulicactuator 212. In particular, the height of the housing 202 may beslightly larger than a diameter of the actuators 208, 212 such that theactuators 208, 212 just fit in the cavity 204. By reducing the height ofthe housing 202, the effective payload is increased and the workspacereorientation envelope is reduced in size.

In operation, the first actuated member 216 may be configured to be in afirst open mode when the first hydraulic actuator 208 is in the firstrelaxing mode, as shown in FIG. 2A. Similarly, the second actuatedmember 218 may be configured to be in a second open mode when the secondhydraulic actuator 212 is in the second relaxing mode, as shown in FIG.2A. In response to sensor data from the force sensor 206, the firstactuated member 216 may be configured to transition to a first closedmode as the first hydraulic actuator 208 is in the first thrusting mode,and the second actuated member 218 may be configured to transition to asecond closed mode as the second hydraulic actuator 212 is in the secondthrusting mode. Such a configuration is illustrated in FIG. 2B.

Although the actuators described herein refer to hydraulic actuators,other kinds of actuators are possible as well, such as pneumaticactuators, or electrical actuators. In the hydraulic actuator example,the actuators 208, 212 are activated by hydraulic pressure, such thatwhen an actuator is configured in the thrusting mode, pressurizedhydraulic fluid is applied in a chamber behind the corresponding pistonof the actuator. When an actuator is configured to be in the relaxingmode, hydraulic fluid is allowed to flow at least unimpeded (andoptionally assisted by suction) out of the chamber. Similar principlesapply if the actuators are powered by pneumatics, solenoids or otherpower sources.

In one example, the gripper 200 may further include a hydraulic channelin fluid communication with both the first hydraulic actuator 208 andthe second hydraulic actuator 212 such that a pressure applied to thefirst actuated member 216 is equal to a pressure applied to the secondactuated member 218. In another example, or as a result of a hardwarereconfiguration, the gripper 200 may include a first hydraulic channelin fluid communication with the first hydraulic actuator 208, and asecond hydraulic channel in fluid communication with the secondhydraulic actuator 212. In such an example, the first actuated member216 and the second actuated member 218 may be individually controllableby pressurized hydraulic fluid from the first hydraulic channel and thesecond hydraulic channel, respectively. As such, a pressure applied tothe first actuated member 216 may be different than a pressure appliedto the second actuated member 218.

In yet another example, the gripper 200 may include a removable sealingcomponent 219 which configures the first hydraulic channel in fluidcommunication with the first hydraulic actuator 208 to be sealed offfrom the second hydraulic channel in fluid communication with the secondhydraulic actuator 212, such that the first actuated member 216 and thesecond actuated member 218 are individually controllable by pressurizedhydraulic fluid from the first hydraulic channel and the secondhydraulic channel, respectively. As such, a pressure applied to thefirst actuated member 216 may be different than a pressure applied tothe second actuated member 218. The removable sealing component 219 maytake the form of a removable pin, for example. As such, a user may beable to easily switch the gripper 200 between a coupled-mode where apressure applied to the first actuated member 216 is equal to a pressureapplied to the second actuated member 218, and anindividually-controllable mode where the first actuated member 216 andthe second actuated member 218 are individually controllable.

As shown in FIGS. 2A and 2B, the first hydraulic actuator 208 mayinclude a first roller surface 220 that contacts a first cam surface 222of the first actuated member 216 to thereby couple the first actuatedmember 216 to the first hydraulic actuator 208. Similarly, the secondhydraulic actuator 212 may include a second roller surface 224 thatcontacts a second cam surface 226 of the second actuated member 218 tothereby couple the second actuated member 218 to the second hydraulicactuator 212. In one example, the first cam surface 222 and the secondcam surface 226 are involute cams, such that a rotation of the firstactuated member 216 and the second actuated member 218 are proportionalto the linear displacement of the respective actuators.

FIG. 2C illustrates an example first hydraulic actuator 208, accordingto an example embodiment. As shown in FIG. 2C, the first hydraulicactuator 208 may include a piston 228 positioned inside of a rod 230. Anend of the rod 230 may include a roller 220 that is coupled to the rod230 via a pin joint 232. The roller 220 may be configured to contact thefirst cam surface 222, as discussed above. Although FIG. 2C referencesthe first hydraulic actuator 208, the second hydraulic actuator 212 maybe similarly configured.

In another embodiment, the first hydraulic actuator 208 may be coupledto the first actuated member 216 via a first pin joint link, and thesecond hydraulic actuator 212 may be coupled to the second actuatedmember 218 via a second pin joint link. In another example, a four-barlinkage may be used to couple the actuated members 216, 218 to therespective hydraulic actuators 208, 212. Other coupling mechanisms arepossible as well.

Further, the gripper 200 may include a first biasing member that biasesthe first hydraulic actuator 208 to the first relaxing mode, and asecond biasing member that biases the second hydraulic actuator 212 tothe second relaxing mode. In one example, such biasing members may betorsion springs. In another example, the hydraulic actuators may receiveconstant pressure from pressurized hydraulic fluid that bias theactuators to their respective relaxing modes. Other example biasingmembers are possible as well.

FIG. 2D illustrates an example first actuated member 216, according toan example embodiment. As shown in FIG. 2D, the first actuated member216 may include a first cam surface 222, and a surface 234. The surface234 may be used to couple a gripping member to the first actuated member216. In one example, the surface 234 may be configured to enable a quickcoupling and decoupling of a variety of gripping members, such that aparticular gripping member could be used for a particular use case.

FIG. 2E illustrates a close up view of the first hydraulic actuator 208as it transitions from the first relaxing mode to the first thrustingmode. As shown in FIG. 2E, the first roller surface 220 contacts thefirst cam surface 222, thereby causing the first actuated member torotate as the first roller surface 220 moves along the first cam surface222. This rotation may be transferred to a gripping member coupled tothe first actuated member 216. Although FIG. 2E references the firsthydraulic actuator 208, the second hydraulic actuator 212 may besimilarly configured.

FIG. 3A illustrates a top view of another gripper 300, according to anexample embodiment. The gripper 300 may include a housing defining acavity. The housing may define a palm of the gripper 300. The gripper300 may also include a force sensor, similar to the example illustratedin FIGS. 2A-2B. The gripper 300 may further include a first hydraulicactuator 302 positioned in the cavity. The first hydraulic actuator 302moves between a first relaxing mode and a first thrusting mode along alongitudinal axis of the first hydraulic actuator 304. The firsthydraulic actuator 302 is shown in the first relaxing mode in FIG. 3A.The first hydraulic actuator 302 may be configured to move between thefirst relaxing mode and the first thrusting mode based at least in partin response to sensor data from the force sensor. For example, thesensor data may be indicative of the gripper 300 contacting an object.As another example, the sensor data may be indicative of the gripper 300contacting a surface on which the object is resting. Other examples ofsensor data are possible as well.

The gripper 300 may further include a second hydraulic actuator 306positioned in the cavity. The second hydraulic actuator 306 may beconfigured to move between a second relaxing mode and a second thrustingmode along a longitudinal axis of the second hydraulic actuator 308. Thesecond hydraulic actuator 306 is shown in the second relaxing mode inFIG. 3A. Similar to the first hydraulic actuator 302, the secondhydraulic actuator 306 may be configured to move between the secondrelaxing mode and the second thrusting mode based at least in part inresponse to sensor data from the force sensor. As shown in FIG. 3A, thelongitudinal axis of the first hydraulic actuator 304 is substantiallyparallel to the longitudinal axis of the second hydraulic actuator 308.

The gripper 300 may further include a third hydraulic actuator 310positioned in the cavity. The third hydraulic actuator 310 may beconfigured to move between a third relaxing mode and a third thrustingmode along a longitudinal axis of the third hydraulic actuator 312. Thethird hydraulic actuator 310 is shown in the second relaxing mode inFIG. 3A. Similar to the first hydraulic actuator 302 and the secondhydraulic actuator 306, the third hydraulic actuator 310 may beconfigured to move between the third relaxing mode and the thirdthrusting mode based at least in part in response to sensor data fromthe force sensor. As shown in FIG. 3A, the longitudinal axis of thefirst hydraulic actuator 304 and the longitudinal axis of the secondhydraulic actuator 308 are substantially parallel to the longitudinalaxis of the third hydraulic actuator 312.

As discussed above, by placing the hydraulic actuators 302, 306, 310 inthe plane of the housing of the gripper 300, the height of the housingcan be minimized. As such, a profile of the housing may be defined by aheight of the first hydraulic actuator 302, a height of the secondhydraulic actuator 306, and a height of the third hydraulic actuator310. In particular, the height of the housing may be slightly largerthan a diameter of the actuators 302, 306, 310 such that the actuators302, 306, 310 just fit in the cavity. By reducing the height of thehousing, the effective payload is increased and the workspacereorientation envelope is reduced in size.

The gripper 300 may further include a first actuated member 314 coupledto the first hydraulic actuator 302, a second actuated member 316coupled to the second hydraulic actuator 306, and a third actuatedmember 318 coupled to the third hydraulic actuator 310.

In operation, the first actuated member 314 may be configured to be in afirst open mode when the first hydraulic actuator 302 is in the firstrelaxing mode, as shown in FIG. 3A. Similarly, the second actuatedmember 316 may be configured to be in a second open mode when the secondhydraulic actuator 306 is in the second relaxing mode, as shown in FIG.3A. And the third actuated member 318 may be configured to be in a thirdopen mode when the third hydraulic actuator 310 is in the third relaxingmode, as shown in FIG. 3A. In response to sensor data from the forcesensor, the first actuated member 314 may be configured to transition toa first closed mode as the first hydraulic actuator 302 is in the firstthrusting mode, the second actuated member 316 may be configured totransition to a second closed mode as the second hydraulic actuator 306is in the second thrusting mode, and the third actuated member 318 maybe configured to transition to a third closed mode as the thirdhydraulic actuator 310 is in the third thrusting mode.

In one example, the gripper 300 may further include a hydraulic channelin fluid communication with each of the first hydraulic actuator 302,the second hydraulic actuator 306, and the third hydraulic actuator 310.As shown in FIG. 3A, the second hydraulic actuator 306 is positionedbetween the first hydraulic actuator 302 and the third hydraulicactuator 310. In such an example, a torque applied to the secondactuated member 316 is approximately double a torque applied to thefirst actuated member 314 and approximately double a torque applied tothe third actuated member 318.

In another example, the gripper 300 may include a first hydraulicchannel in fluid communication with the first hydraulic actuator 302, asecond hydraulic channel in fluid communication with the secondhydraulic actuator 306, and a third hydraulic channel in fluidcommunication with the third hydraulic actuator 310. In such an example,each of the first actuated member 314, the second actuated member 316,and the third actuated member 318 may be individually controllable bypressurized hydraulic fluid from the first hydraulic channel, the secondhydraulic channel, and the third hydraulic channel, respectively. Assuch, a pressure applied to the first actuated member 314 may bedifferent from a pressure applied to the second actuated member 316,which in turn may be different from a pressure applied to the thirdactuated member 318.

In yet another example, the gripper 300 may include one or moreremovable sealing components 319 which configure the first hydraulicchannel in fluid communication with the first hydraulic actuator 302 tobe sealed off from one or more of a second hydraulic channel in fluidcommunication with the second hydraulic actuator 306 and a thirdhydraulic channel in fluid communication with the third hydraulicactuator 310, such that each of the first actuated member 314, thesecond actuated member 316, and the third actuated member 318 areindividually controllable. As such, a pressure applied to the firstactuated member 314 may be different from a pressure applied to thesecond actuated member 316, which in turn may be different from apressure applied to the third actuated member 318. The removable sealingcomponent 319 may take the form of a removable pin, for example. Assuch, a user may be able to easily switch the gripper 300 between acoupled-mode where a torque applied to the second actuated member 316 isapproximately double a torque applied to the first actuated member 314and approximately double a torque applied to the third actuated member318, and an individually-controllable mode where each of the firstactuated member 314, the second actuated member 316, and the thirdactuated member 318 are individually controllable.

FIG. 3B illustrates various components of the gripper 300. Inparticular, FIG. 3B illustrates the first hydraulic actuator 302including a first roller surface 320. The first roller surface 320 maybe configured to contact a first cam surface 322 of the first actuatedmember 314 to thereby couple the first actuated member 314 to the firsthydraulic actuator 302. Further, the first actuated member 314 mayinclude a surface 324. Similarly, the second hydraulic actuator 306 mayinclude a second roller surface 326 configured to contact a second camsurface 328 of the second actuated member 316 to thereby couple thesecond actuated member 316 to the second hydraulic actuator 306. Thesecond actuated member 316 may further include a surface 330. Further,the third hydraulic actuator 310 may include a third roller surface 332configured to contact a third cam surface 334 of the third actuatedmember 318 to thereby couple the third actuated member 318 to the thirdhydraulic actuator 310. The third actuated member 318 may furtherinclude a surface 336. In one example, the first cam surface 322, thesecond cam surface 328, and the third cam surface 334 are involute cams,such that a rotation of the first actuated member 314, the secondactuated member 316, and the third actuated member 318 are proportionalto the linear displacement of the respective actuators. Further, in suchan example, a contact force between the involute cam surfaces and thecorresponding roller surface is always aligned with the longitudinalactuator axis.

A given surface 324, 330, 336 may be used to couple a gripping member toa respective actuated member 314, 316, 318. In one example, suchsurfaces may be configured to enable a quick coupling and decoupling ofa variety of gripping members, such that a particular gripping membercould be used for a particular use case.

FIGS. 3C and 3D illustrate various gripping members that may be attachedto gripper 300, according to example implementations. As discussedabove, the gripper 300 may be configured such that various grippingmembers can be attached based on a particular use case. In particular,FIG. 3C illustrates an example gripper 300 including curved grippingmembers. Such gripping members may be used to grasp circular orcylindrical objects, for example. FIG. 3D illustrates an example gripper300 including adaptive fingers that may be used to grasp oddly shapedobjects, for example.

It should be noted that other grippers may include more or lesscomponents than those that are shown in FIGS. 2A, 2B, 2C, 2D, 2E, 3A,3B, 3C, and 3D. For instance, in other implementations, the gripper mayinclude more or less motors, gears, and/or axles. Additionally oralternatively, the number of linkages may vary depending on thekinematics and grip force that is required to have the gripper perform aparticular task. For instance, in some arrangements, the linkages may beeliminated, and the gripping tips and/or other components may be coupleddirectly or almost directly to the axle(s). Overall, such additional orreduced components may drive operations of the gripper described hereinor perhaps other operations of the gripper not described herein. By wayof example, such components may serve to drive individual actuation ofeach separate finger independently from other fingers, includingsubstantially linear actuation of an individual finger and/or rotationalactuation of the individual finger. Other operations are possible aswell.

It should also be noted that while the gripping fingers are shown to besubstantially symmetrical and including the same elements, each grippingfinger may include one or more elements different from the othergripping finger.

In operation, it may be advantageous for the control system to determineor receive various information associated with the object(s) at issue,such as the locations, dimensions, weights, centers of mass, etc. of theobject(s), in order to help the control system determine how to actuatethe robotic gripper and/or other aspects of the robotic device toperform certain tasks. Within examples, the control system may determinedegrees and/or speeds of rotation of the gripping fingers based on howmuch force and torque the control system knows the gripping fingers canhandle.

Further, with the freedom that the disclosed gripper provides, a controlsystem can dynamically adjust movement of the gripper based on changingconditions in the environment, such as the weight of the object shiftingwhile the object is being moved, obstacles present in the environment asthe gripper is navigated through the environment from one location toanother, among other possibilities. To facilitate this, force sensors,torque sensors, cameras, etc. of the robotic device may keep the controlsystem informed of (i) what force/torque is exerted on the finger(s),(ii) where in the environment the gripper is located, (iii) whatobstacles are present in the environment, etc.

FIG. 4 is a flow chart of an example method for controlling a roboticgripper to pick up and grasp an object. The method shown in FIG. 4presents an implementation of a method that, for example, could be usedwith the system shown in FIG. 1 and/or with the systems and apparatusesshown in FIGS. 2A, 2B, 2C, 2D, 2E, 3A, 3B, 3C, and/or 3D, for example,or may be performed by a combination of any components of in thesefigures. The method may include one or more operations, or actions asillustrated by one or more of blocks 400, 402, 404, 406, and 408.Although the blocks are illustrated in a sequential order, these blocksmay in some instances be performed in parallel, and/or in a differentorder than those described herein. Also, the various blocks may becombined into fewer blocks, divided into additional blocks, and/orremoved based upon the desired implementation.

In addition, for the method and other processes and methods disclosedherein, the flowchart shows operation of one possible implementation ofpresent implementations. In this regard, each block may represent amodule, a segment, or a portion of program code, which includes one ormore instructions executable by one or more processors for implementingspecific logical operations or steps in the process. The program codemay be stored on any type of computer readable medium, for example, suchas a storage device including a disk or hard drive. The computerreadable medium may include a non-transitory computer readable medium,for example, such as computer-readable media that stores data for shortperiods of time like register memory, processor cache and Random AccessMemory (RAM). The computer readable medium may also includenon-transitory media, such as secondary or persistent long term storage,like read only memory (ROM), optical or magnetic disks, compact-discread only memory (CD-ROM), for example. The computer readable media mayalso be any other volatile or non-volatile storage systems. The computerreadable medium may be considered a computer readable storage medium, atangible storage device, or other article of manufacture, for example.

In addition, for the method and other processes and methods disclosedherein, each block in FIG. 4 may represent circuitry that is wired toperform the specific logical operations in the process.

Operations of this example method, and operations of other methods andprocesses disclosed herein, may be performed at least in part by acontrol system configured control a robotic device and/or othercomponents or subsystems (e.g., sensors or another type of roboticvision system located remotely from the system) that are associated withthe robotic device, such as control system 106 and/or other subsystemsof robotic device 100 described above.

At block 400, the control system receives data indicative of a distinctlocation of an object in an environment of the device, and furtherindicative of a dimension of the object. Within examples, the data maybe based at least in part on information obtained by a vision system ofthe robotic device and/or by a system configured to store and maintain alocation of the object. Further, the data may include a 2D image or 3Dmodel of the environment that indicates where in the environment theobject is located. Still further, the data may include coordinates ofthe object. Yet still further, the data may include dimensions of theobject and/or a weight of the object, as noted above.

At block 402, the control system determines, based on the location anddimension of the object, positions to which to rotate each of the firstand second gripping members such that the object is located between thefirst and second gripping members.

In some implementations, the positions to which the control system moveseach gripping member may be based on other considerations as well. Byway of example, the positions may be based at least in part on otherinformation included in the received data, such as the dimensions theobject. Accordingly, the distance at which the control system separatesthe gripping members may be based on how much space is needed betweenthe gripping members for the object, for instance. As another example,the positions to which the control system moves gripping members may bebased at least in part on locations of other objects in the environment.To facilitate this, the control system may receive other data indicativeof the surrounding environment of the gripper through which the gripperwill need to navigate in order to approach and grasp the object withoutinterfering with (e.g., contacting) certain other objects in theenvironment. In this manner, if the gripper is navigating a tight spaceto grasp the object, for instance, the control system may not separatethe gripping members too far apart and/or may not rotate the grippingmembers to a degree where the gripper might contact other objects. Otherexamples are possible as well.

Within examples, the control system may receive the data before thegripper is near the object and may thus determine or estimate thesepositions as part of a process in which the control system plans inadvance a task for the robotic device to complete. Within otherexamples, the data may be based at least in part on information obtainedby sensors coupled to the gripper itself, and thus the control systemmay not determine or estimate these positions until the gripper is closeenough to the object to properly obtain this information.

At block 404, the control system causes first and second grippingmembers to rotate to the determined positions. At block 406, the controlsystem receives sensor data from the force sensor of the gripper. Asdiscussed above, the sensor data may be indicative of the grippercontacting the object. As another example, the sensor data may beindicative of the gripper contacting a surface on which the object isresting. Other examples of sensor data are possible as well. And atblock 408, in response to the received sensor data, the control systemcauses movement of the first and second gripping members toward eachother so as to grasp the object. Once the object has been grasped, theforce sensor may provide information indicative of various massproperties of the object, such as a weight of the object, and/ordimensions of the object.

It should be understood that arrangements described herein are forpurposes of example only. As such, those skilled in the art willappreciate that other arrangements and other elements (e.g. machines,interfaces, operations, orders, and groupings of operations, etc.) canbe used instead, and some elements may be omitted altogether accordingto the desired results. Further, many of the elements that are describedare operational entities that may be implemented as discrete ordistributed components or in conjunction with other components, in anysuitable combination and location, or other structural elementsdescribed as independent structures may be combined.

While various aspects and implementations have been disclosed herein,other aspects and implementations will be apparent to those skilled inthe art. The various aspects and implementations disclosed herein arefor purposes of illustration and are not intended to be limiting, withthe true scope being indicated by the following claims, along with thefull scope of equivalents to which such claims are entitled. It is alsoto be understood that the terminology used herein is for the purpose ofdescribing particular implementations only, and is not intended to belimiting.

What is claimed is:
 1. A device comprising: a housing defining a cavity;a force sensor; a first hydraulic actuator positioned in the cavity,wherein the first hydraulic actuator moves between a first relaxing modeand a first thrusting mode along a longitudinal axis of the firsthydraulic actuator based at least in part in response to sensor datafrom the force sensor; a second hydraulic actuator positioned in thecavity, wherein the second hydraulic actuator moves between a secondrelaxing mode and a second thrusting mode along a longitudinal axis ofthe second hydraulic actuator based at least in part in response tosensor data from the force sensor, and wherein the longitudinal axis ofthe first hydraulic actuator is substantially parallel to thelongitudinal axis of the second hydraulic actuator; a third hydraulicactuator positioned in the cavity, wherein the third hydraulic actuatormoves between a third relaxing mode and a third thrusting mode along alongitudinal axis of the third hydraulic actuator based at least in partin response to sensor data from the force sensor, wherein thelongitudinal axis of the first hydraulic actuator and the longitudinalaxis of the second hydraulic actuator are substantially parallel to thelongitudinal axis of the third hydraulic actuator, and wherein thesecond hydraulic actuator is positioned between the first hydraulicactuator and the third hydraulic actuator in the cavity; a firstactuated member coupled to the first hydraulic actuator, wherein thefirst actuated member is in a first open mode when the first hydraulicactuator is in the first relaxing mode, and wherein the first actuatedmember is in a first closed mode when the first hydraulic actuator is inthe first thrusting mode; a second actuated member coupled to the secondhydraulic actuator, wherein the second actuated member is in a secondopen mode when the second hydraulic actuator is in the second relaxingmode, and wherein the second actuated member is in a second closed modewhen the second hydraulic actuator is in the second thrusting mode; anda third actuated member coupled to the third hydraulic actuator, whereinthe third actuated member is in a third open mode when the thirdhydraulic actuator is in the third relaxing mode, wherein the thirdactuated member is in a third closed mode when the third hydraulicactuator is in the third thrusting mode, and wherein a torque applied tothe second actuated member is approximately double a torque applied tothe first actuated member and approximately double a torque applied tothe third actuated member.
 2. The device of claim 1, wherein the firsthydraulic actuator includes a first roller surface that contacts a firstcam surface of the first actuated member to couple the first actuatedmember to the first hydraulic actuator, wherein the second hydraulicactuator includes a second roller surface that contacts a second camsurface of the second actuated member to couple the second actuatedmember to the second hydraulic actuator, and wherein the third hydraulicactuator includes a third roller surface that contacts a third camsurface of the third actuated member to couple the third actuated memberto the third hydraulic actuator.
 3. The device of claim 2, wherein thefirst cam surface, the second cam surface, and the third cam surfaceeach include involute cam surfaces.
 4. The device of claim 1, furthercomprising: a first biasing member that biases the first hydraulicactuator to the first relaxing mode; a second biasing member that biasesthe second hydraulic actuator to the second relaxing mode; and a thirdbiasing member that biases the third hydraulic actuator to the thirdrelaxing mode.
 5. The device of claim 1, further comprising: a firstencoder coupled to the first actuated member to provide data indicativeof motion of the first actuated member, wherein a controller causes thefirst actuated member to rotate based on the controller causing thefirst hydraulic actuator to move between the first relaxing mode and thefirst thrusting mode; a second encoder coupled to the second actuatedmember to provide data indicative of motion of the second actuatedmember, wherein the controller causes the second actuated member torotate based on the controller causing the second hydraulic actuator tomove between the second relaxing mode and the second thrusting mode; anda third encoder coupled to the third actuated member to provide dataindicative of motion of the third actuated member, wherein thecontroller causes the third actuated member to rotate based on thecontroller causing the third hydraulic actuator to move between thethird relaxing mode and the third thrusting mode.
 6. The device of claim1, further comprising: a hydraulic channel in fluid communication witheach of the first hydraulic actuator, the second hydraulic actuator, andthe third hydraulic actuator.
 7. The device of claim 6, furthercomprising: one or more removable sealing components which configure afirst hydraulic channel in fluid communication with the first hydraulicactuator to be sealed off from one or more of a second hydraulic channelin fluid communication with the second hydraulic actuator and a thirdhydraulic channel in fluid communication with the third hydraulicactuator, such that each of the first actuated member, the secondactuated member, and the third actuated member are individuallycontrollable.
 8. The device of claim 1, further comprising: a firsthydraulic channel in fluid communication with the first hydraulicactuator; a second hydraulic channel in fluid communication with thesecond hydraulic actuator; and a third hydraulic channel in fluidcommunication with the third hydraulic actuator, such that each of thefirst actuated member, the second actuated member, and the thirdactuated member are individually controllable.
 9. The device of claim 1,wherein a profile of the housing is defined by a height of the firsthydraulic actuator, a height of the second hydraulic actuator, and aheight of the third hydraulic actuator.
 10. A robotic device,comprising: a first limb; a second limb coupled to the first limb; agripping component coupled to the second limb, wherein the grippingcomponent comprises (i) a housing defining a cavity, (ii) a forcesensor, (iii) a first hydraulic actuator positioned in the cavity,wherein the first hydraulic actuator moves between a first relaxing modeand a first thrusting mode along a longitudinal axis of the firsthydraulic actuator, (iv) a second hydraulic actuator positioned in thecavity, wherein the second hydraulic actuator moves between a secondrelaxing mode and a second thrusting mode along a longitudinal axis ofthe second hydraulic actuator, and wherein the longitudinal axis of thefirst hydraulic actuator is substantially parallel to the longitudinalaxis of the second hydraulic actuator, (v) a third hydraulic actuatorpositioned in the cavity, wherein the third hydraulic actuator movesbetween a third relaxing mode and a third thrusting mode along alongitudinal axis of the third hydraulic actuator, wherein thelongitudinal axis of the first hydraulic actuator and the longitudinalaxis of the second hydraulic actuator are substantially parallel to thelongitudinal axis of the third hydraulic actuator, and wherein thesecond hydraulic actuator is positioned between the first hydraulicactuator and the third hydraulic actuator in the cavity, (vi) a firstgripping member coupled to the first hydraulic actuator, (vii) a secondgripping member coupled to the second hydraulic actuator, and (viii) athird gripping member coupled to the third hydraulic actuator, wherein atorque applied to the second gripping member is approximately double atorque applied to the first gripping member and approximately double atorque applied to the third gripping member; and a controller comprisingat least one processor and data storage comprising instructionsexecutable by the at least one processor to cause the controller toperform operations comprising: based at least in part in response tosensor data from the force sensor, causing the first, second, and thirdhydraulic actuators to move between the first, second, and thirdrelaxing modes and the first, second, and third thrusting modes tothereby cause movements of the first, second, and third gripping membersso as to grasp one or more objects.
 11. The robotic device of claim 10,wherein the operations further comprise: receiving data indicative of anobject in an environment of the robotic device, the data including alocation of the object in the environment; based on the location of theobject, determining a position to which to rotate each of the first,second, and third gripping members such that the object is locatedbetween the first, second, and third gripping members; causing thefirst, second, and third gripping members to rotate to the determinedposition; and causing movement of the first, second, and third grippingmembers so as to grasp the object.
 12. The robotic device of claim 10,wherein the gripping component further comprises: a first biasing memberthat biases the first hydraulic actuator to the first relaxing mode; asecond biasing member that biases the second hydraulic actuator to thesecond relaxing mode; and a third biasing member that biases the thirdhydraulic actuator to the third relaxing mode.
 13. The robotic device ofclaim 10, wherein the gripping component further comprises: a firstencoder coupled to the first gripping member to provide data indicativeof motion of the first gripping member, wherein a controller causes thefirst gripping member to rotate based on the controller causing thefirst hydraulic actuator to move between the first relaxing mode and thefirst thrusting mode; a second encoder coupled to the second grippingmember to provide data indicative of motion of the second grippingmember, wherein the controller causes the second gripping member torotate based on the controller causing the second hydraulic actuator tomove between the second relaxing mode and the second thrusting mode; anda third encoder coupled to the third gripping member to provide dataindicative of motion of the third gripping member, wherein thecontroller causes the third gripping member to rotate based on thecontroller causing the third hydraulic actuator to move between thethird relaxing mode and the third thrusting mode.
 14. The robotic deviceof claim 10, further comprising: a hydraulic channel in fluidcommunication with each of the first hydraulic actuator, the secondhydraulic actuator and the third hydraulic actuator.
 15. The roboticdevice of claim 10, further comprising: a first hydraulic channel influid communication with the first hydraulic actuator; a secondhydraulic channel in fluid communication with the second hydraulicactuator; and a third hydraulic channel in fluid communication with thethird hydraulic actuator, such that each of the first actuated member,the second actuated member, and the third actuated member areindividually controllable.
 16. The robotic device of claim 10, wherein aprofile of the housing is defined by a height of the first hydraulicactuator, a height of the second hydraulic actuator, and a height of thethird hydraulic actuator.
 17. A method for actuating a device comprising(i) a housing defining a cavity, (ii) a force sensor, (iii) a firsthydraulic actuator positioned in the cavity, wherein the first hydraulicactuator moves between a first relaxing mode and a first thrusting modealong a longitudinal axis of the first hydraulic actuator, (iv) a secondhydraulic actuator positioned in the cavity, wherein the secondhydraulic actuator moves between a second relaxing mode and a secondthrusting mode along a longitudinal axis of the second hydraulicactuator, and wherein the longitudinal axis of the first hydraulicactuator is substantially parallel to the longitudinal axis of thesecond hydraulic actuator, (v) a first gripping member coupled to thefirst hydraulic actuator, and (vi) a second gripping member coupled tothe second hydraulic actuator, the method comprising: receiving, at acontrol system configured to actuate the device, data indicative of adistinct location of an object in an environment of the device andfurther indicative of a dimension of the object; based on the locationand dimension of the object, determining a position to which to rotateeach of the first and second gripping members such that the object islocated between the first and second gripping members; causing the firstand second gripping members to rotate to the determined position;receiving, at the control system, sensor data from the force sensor; andin response to the received sensor data, causing movement of the firstand second gripping members so as to grasp the object.